Complex formation of mono-and binuclear dimeric cyclophane zinc diphenylporphyrinates with pyridine

The formation of host-guest complexes between zinc diphenylporphyrinates of dimeric diphenylporphyrins and pyridine in toluene has been studied by the spectrophotometric titration method and ¹H NMR spectroscopy. The zinc porphyrinates with pyridine form “internal” or “external” 1: 1 or 1: 2 complexes, depending on the length of binding ether O(CH₂)_nO bridges (n = 2, 3) of the cyclophane dimers and the reactant concentration. The stability constants of the porphyrinate-ligand complexes and concentration ranges of their formation have been determined.